Foam Insulation Under Headliner?

[sgharford]

I searched and couldn’t find any info on Sam’s, so here we go: I’m putting up new headliner in main saloon and v-berth of 43DC. Going with perforated and stapled, same as original installation. Talking to some locals, they are recommending I put in ½” foam board insulation (closed cell type found at Home Depot - http://www.homedepot.com/buy/insl-sheating-12-in-x-48-in-x-96-in-20897.html) before putting up headliner. I was thinking cutting it for a tight fit and leaving ¼” between lower skin of deck and ¼” of new headliner – spraying some “Great Stuff” foam in dabs on lower skin of deck to keep in place and level, along with some short screws protruding from lower end rafters (?) incase Great Stuff gives way the board could rest on screws rather than headliner.

Some further info, I'm in North East (Long Island Sound) and would like to keep boat in water this winter, so extra insulation would be a bonus. I hear this also helps keeping boat cooler in summer as well as helps with sound deadening.

So what do you guys think – good idea or bad idea? What should I watch out for if I go this route? Heart telling me not to do it at all, but now is the time to consider before 2000+ Monel staples go back in place.

 

[Boatsb]

Check the fire rating on the foam board. If its acceptable for marine interior and breathing air spaces go for it. If not find a foam that is.

 

[saltshaker]

I'm not so sure I would do it. Condensation can form on the underside of the decks. If the foam is there is may prevent the surface from drying. Isn't that the function of the perforated headliner? That being said, most newer boats have a solid headliner but I'm not sure if there is any ventilation between the two surfaces. I'd make a call to Hatteras or someone who has experience with installing headliners. I believe Whisper Wall has a foam backing but it's all part of the headliner.

 

[sgharford]

Good point you brought up about pink foam board - fumes from it are extremely toxic if fire and risk that one takes using it.

Reckon Condensation is the biggest worry about using insulation - last thing I need with a stapled in headliner. Additional warmth in winter would be big bonus, but with as large as single pane windows are in main saloon , how much will I really gain? Reading other forums, people who have done it seem to have good experiences doing so, but I could not find specific reference to one that involved perforated stapled in headliner.

 

[saltshaker]

Good point you brought up about pink foam board - fumes from it are extremely toxic if fire and risk that one takes using it.

Reckon Condensation is the biggest worry about using insulation - last thing I need with a stapled in headliner. Additional warmth in winter would be big bonus, but with as large as single pane windows are in main saloon , how much will I really gain? Reading other forums, people who have done it seem to have good experiences doing so, but I could not find specific reference to one that involved perforated stapled in headliner.

You'll be surprised how warm it will stay inside the boat during the winter. I keep all the blinds up so I get a lot of sun during the day. One year I decided to leave a bowl of water on the counter in the salon. I was working a few miles from the boat so I was checking on it daily. We had a cold winter that year and had several times when it was in the teens for a week or more. The water in the bowl never froze. I didn't have any heaters running unless I was on board for a while. Do you have block heaters? If not they are a must for in water winter storage. They keep the ER dry and toasty warm. They're also great if you want to use the boat late in the fall or early winter. Besides the freeze protection, they'll keep the condensation down both internally and externally for the engines.

 

[sgharford]

I do have block heaters

Did you insulate under headliner? Also, If anyone knows of a marine rated 1/2" thick fire proof board, with preferable high R value, I'm all ears. I’m googling and nothing coming up for me. Mounting suggestions welcome as well. And of course, still open as to whether any of this a good idea to begin with.

 

[sgharford]

I think BoatsB summed it up very eloquently. Since there were minimal problems with original headliner after 36 years of use, I'm going to skip any additional insulation above the headliner. It seemed like interesting prospect, but I'm worried I'll create a mold problem that never existed and not being able to find right material (the pink foam board is extremely toxic when it readily catches fire and is only rated for outdoor use), seems hard to justify additional expense and labor to make it happen. Nothing ventured nothing gained. Thanks again Scott and Jack for feedback - Scott.

 

[saltshaker]

I do have block heaters

Did you insulate under headliner? Also, If anyone knows of a marine rated 1/2" thick fire proof board, with preferable high R value, I'm all ears. I’m googling and nothing coming up for me. Mounting suggestions welcome as well. And of course, still open as to whether any of this a good idea to begin with.

No additional insulation when the headliner was changed on my 46C. My 65 also has new headliner. It was done before I bought the boat and I don't know if there is any insulation above it. I was speaking to Tom Slane this AM and I asked him his thoughts on this. He said he hasn't used insulation but you can if you want. He said that sweating isn't a problem because of the cored decks. He did mention that 3M made a product that others have used, primarily for sound deadening.

 

[Fanfare]

I added a rigid foam insulation many years ago the first time I renovated the headliner. Have had no problems with mold. Now on the third headliner. I don't have any balsa on the outer portions of the bridge deck and was not sure about the center so figured more insulation couldn't hurt. The only part I do know about is where the helm seat on the bridge attaches, and here there is only about 1/2 in. of glass alone. Unlike the 53MY my 50MY has a smooth finished flat cover beneath the cabin overhead so it is not visable.

 

[sdowney717]

I think I would use the aluminum faced polyisocyanurate insulation board like you will find at HD or lowes. Comes in 4 by 8 1/2 inch sheets. I would consider doubling it up facing the foil outward on both sides. It is rated to 225 or 250 degrees. There is a lot of damaging chemicals released from all the materials on a boat on fire that this would be a minor item dont you think?

Looks like you can get it in various thicknesses. Under my headliner there is a foil faced paper but no insulation.

http://www.pima.org/contentpage/ContentPage.aspx?ModuleID=5&SubModuleID=45

Its many attributes include:

Highest R-value per inch of thickness
Moisture resistant, water repellent panel
Resistant to solvents used in construction adhesives
Excellent dimensional stability
Superior performance in fire tests – polyiso meets the strict standard of both FM Class Approvals 1 UL 1256/ULC S126
Service temperature range from -75 F (-60 C) to +225 F (+107 C) to reflect Canadian and US material standards
Long Term R-value (only roof insulation with third party certification)
Recycled content
Zero ozone depletion potential
Virtually no global warming potential
Nationwide availability

 

[sgharford]

1000th post! Boy, I'm ready to crack a beer instead of doing this job and you guys pull me back in! Thanks You very much Jack for checking with Tom Slane, that was really very nice of you. So on other sites I found on this topic, folks where posting what a great insulator wood is. I just checked R value of plywood and it's around 1.2 per inch. I just replaced most of core with basically 3/4 plywood, so that's a pretty lousy R factor. Looking at the Polyiso product sdowney717 recommended (another hearty Thank You), I found R factor of 3.3 per 1/2" which would significantly increase ceiling insulation. As for fire rating, the pink Owen's stuff ok up to 165 degrees, at least Polyiso is 225 degrees. And sdowney717, your right about all the other combustible stuff. I have 3 very young (none swimming) children on board, with what just happened in Oyster Bay (about 10 miles on the water from me), I'm feeling less risky. I did have a Ford Bronco with fiberglass rear top catch on fire, seeing the fumes that top gave off I would have to agree that the pink board would probably not contribute much to cocktail of deadly combustible's already on board. So maybe a trip tonight to Home Depot in the mini-van to check out the Polyiso material. But I’ll do some checking on 3M materials before I do that.

So saying I go with ½” Polyiso, how would you guys recommend installing it? Let’s take main saloon, there are approximately 10 1”x6” rafters spaced 2’ apart. There is actually about 1.25” of space between exposed fiberglass ceiling and bottom of rafter headliner will attach to as the rafter is bonded with approximately 0.25” of fiberglass filler. There are wires for lighting and speakers tied to fiberglass ceiling, so ¼” spacing handy for that reason as well as additional insulation. Can I just compression fit between rafters? Now that I’m thinking about it, I need some space on vertical sections of rafter to staple the headliner to. Guess a ½” should be enough for that, all I have left.

 

[sdowney717]

This is a very light weight insulation.
I would glue it in place with PL premium construction adhesive, just a few dabs here and there then tape it up temporarily somehow to hold it where you wish. Or you can use the aluminum duct tape which would be quick and easy.
Face the aluminum side towards the heat, right?
It is 10$ per 4 by 8 board.
You could also put in twice the layer with foil facing out and paper side on inside which will double the R value and reflect heat energy from both sides.

At Lowes and HD it is called RMax insulation board.

 

[sgharford]

Great Info! The local Lowe's has it in stock. I'm meeting fella doing headliner tomorrow morning at boat to go over job. He was one of folks who suggested foam board insulation. I'll make sure he's still on board and the 1/2 inch of room left on rafter will be enough to staple to. Glad the thread kept going as I was banking on cored deck being better insulator that it appears to be prior to checking R factor for myself. This should make a noticeable improvement if done right.

 

[GJH]

If you have block heaters, leave the hatches open (in the salon on a 43DC, right?) and they will give you great radiant heat; make sure the ER vents are closed up with something, such as the insulation you are considering, things will stay nice and dry. On our 56MY, we leave the doors open for the same effect and it has served us well during a couple of wet and cold winters. Never occured to me to insulate , but should help to keep the warmth in.
Have you taken a look up under the liner yet? At least on my boat there is a fair amount of wiring up there I'd want to maintain some access to.

 

[sgharford]

Glad those block heaters are finally going to get used, not an easy installation on Cummins 903 as all appendages on front of engine has to come off to get at access plate they replace. I didn't realize they would make such good heaters for rest of boat, but makes sense they would. They are pretty big too, 1500W for each engine. May even have to put thermostats on them (fall project!). Good idea covering engine room air intake vents, I'll keep that in mind when day comes.

I have the liner down and all new wiring for 12Vdc LED lights in. I'm running a couple of extra sets of wires here and there for some possible future accessories while everything is down. Regarding access, way I figure is no one needed to get up there for 36 years, so hopefully I won't either. I am keeping 2 of 3 existing junction hatches in liner, but that's it. I got rid of mast, nav lights, and horns on deck above salon, so that eliminated all but the speaker and interior wire lights are there now. Also a bonus as those items were major cause of leak and why deck core had to be replaced.

 

[Boatsb]

Remember fiberglass and rockwool can work and wont be a fire issue.

I will probably use fiberglass when I redo mine.

 

[GJH]

If you have 1500's absolutely get the thermostats. My 8v92's have 1000 watt units with 100 degree thermostats and keep things very nice and warm. It will help your electric bill too.

 

[saltshaker]

If you have 1500's absolutely get the thermostats. My 8v92's have 1000 watt units with 100 degree thermostats and keep things very nice and warm. It will help your electric bill too.

X2. I had 1500W units in my 6V92's. Set the tstats to 110 and they would cycle on and off even when outside temps were near 0.

 

[dsharp]

Claremont makes several types of fire rated insulation. They refer to it as hullboard.

 

[q240z]

If you use the panel insulation and don't have the edges sealed up all the way around, condensation will form on the roof when it's cold outside. The condensation will freeze. Then, when outside temps warm a bit, it will melt and you will get lots of runoff.

When it happened to me, I still hadn't installed my headliner. I ripped down all of the panels and reinstalled them using expanding foam to fully seal the panels all the way around. Problems solved.

An ice storm came through after the install. Three days later, I still had a solid sheet of ice on my salon roof and aft deck while the ice had long since melted off of neighboring boats that were radiating heat from their interiors. It really does keep the heat on the inside.